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Monday, December 03, 2018

Scientists Reveal Substantial Water Loss in Global Landlocked Regions

Along with a warming climate and intensified human activities, recent water storage in global landlocked basins has undergone a widespread decline. A new study reveals this decline has aggravated local water stress and caused potential sea level rise.The study, "Recent Global Decline in Endorheic Basin Water Storage," was carried out by a team of scientists from six countries and appears in the current issue of Nature Geoscience."Water resources are extremely limited in the continental hinterlands where streamflow does not reach the ocean. Scientifically, these regions are called endorheic basins," said Jida Wang, a Kansas State University geographer and the study's lead author."Over the past few decades, we have seen increasing evidence of perturbations to the endorheic water balance," said Wang, an assistant professor of geography. "This includes, for example, the desiccating Aral Sea, the depleting Arabian aquifer and the retreating Eurasian glaciers. This evidence motivated us to ask: Is the total water storage across the global endorheic system, about one-fifth of the continental surface, undergoing a net decline?"Using gravity observations from NASA/German Aerospace Center's Gravity Recovery and Climate Experiment, or GRACE, satellites, Wang and his colleagues quantified a net water loss in global endorheic basins of approximately 100 billion tons of water per year since the start of the current millennium. This means a water mass equivalent to five Great Salt Lakes or three Lake Meads is gone every year from the arid endorheic regions.Surprisingly, this amount of endorheic water loss is double the rate of concurrent water changes across the remaining landmass except Greenland and Antarctica, Wang said. Opposite to endorheic basins, the remaining regions are exorheic, meaning streamflow originating from these basins drains to the ocean. Exorheic basins account for most of the continental surface and are home to many of the world's greatest rivers, such as the Nile, Amazon, Yangtze, and Mississippi.Read more at Scientists Reveal Substantial Water Loss in Global Landlocked Regions